As per a study released on Monday, sniffer dogs can be trained to identify more than 90% of COVID-19 infections even when patients are asymptomatic, which scientists believe will help replace the requirement to confine new arrivals.

Dogs have already demonstrated that they can detect cancer, malaria, and epilepsy using their extraordinary sense of smell that can detect the equivalent of half a teaspoon of sugar in an Olympic-sized swimming pool.

Several prior investigations have demonstrated that dogs can identify SARS-CoV-2. Even the fastest COVID-19 tests take 15 minutes to get a result, while the dogs can detect the condition in seconds. As per the researchers, this means that two dogs can check 300 persons in half an hour.

This might render the sniff test "a feasible tool for mass screening," as per Professor Logan of the London School of Hygiene and Tropical Medicine. To assist prevent a super-spreading incident; bulk scanning could be performed at airports or major rail stations.

The dogs detected around 88% of positive cases, which means that for every 100 cases, the dogs missed just 12 sick persons. Yet, out of 100 persons who did not have COVID-19, the dogs incorrectly claimed that 14 of them have been infected using the smell test.

As a result, the study team does not propose using dogs alone to seek out positive cases, but rather use them as an extra screening tool alongside more traditional testing. The London School of Tropical Medicine sought to determine if dogs could find the exact odor emitted by chemical components linked with people who are COVID-19 positive but do not exhibit symptoms.

They collected clothes and face mask samples from persons who tested positive with mild or symptomatic SARS-CoV-2. Sock samples from 200 COVID-19 patients were gathered and placed in lab testing for six dogs trained to recognize the presence or absence of the chemical component.

The dogs would have to be trained not to detect "false positives" to breach their reward system and earn treats even when no COVID-19 samples were present in a specific test. "This implies the dog completely understands and receives a reward for both a right negative and a right positive," explained Claire Guest of the school's Faculty of Infectious and Tropical Diseases.

Generally, the dogs were effective in identifying between 94 and 82% of SARS-CoV-2 specimens. The researchers then calculated how well these success rates, when paired with regular PCR testing, may aid in the detection of moderate or asymptomatic COVID-19 patients. They discovered that scanning arrivals at terminals such as airports using dogs could detect 91% of cases, leading to a 2.24 times lower incidence of transmission than PCR testing alone.

The authors of the study, which has yet to be peer-reviewed, expressed hope that it will someday eliminate the requirement for passengers to quarantine, which disturbs every arrival even if the large proportion are not COVID-19 positive. "The main point is that dogs are substantially faster than previous tests," co-author James Logan explained. "What we recommend is that dogs perform the first screening, and then those (arrivals) who are found to be positive receive a complementary PCR test."

As per the research, less than 1% of a planeload of passengers — around 300 passengers — were statistically more likely to be carrying SARS-CoV-2. Under present quarantine restrictions in effect in some nations, all 300 would be required to isolate, which would be extremely inconvenient. However, given the sensitivity of trained dogs, the study said that a maximum of 35 humans on board will be identified as positive. Only around three of them are predicted to get a positive PCR test.

"That's a crucial start and might lead to a viable, practical system," said Mick Bailey, a professor of Comparative Immunology at the University of Bristol who has not been part of the study.

"We require a lot more confirmation before we can be convinced that dogs can effectively and accurately diagnose asymptomatic SARS-CoV-2 infection in individuals in airports and railway stations."